Buggy code:
public class StatisticPanel extends JPanel { private JPanel upperPanel ; private JPanel lowerPanel ; private JButton weekButton ; private JButton monthButton ; private JButton yearButton ; private JLabel amountSold ; private JLabel cashIn ; private JLabel titel ; private JLabel firstEmpty ; private JLabel secondEmpty ; private JLabel thirdEmpty ; private JLabel rubrik ; private JScrollPane firstPane ; private JScrollPane secondPane ; private JScrollPane thirdPane ; private JTable titleTable ; private JTable amountTable ; private JTable cashInTable ; public StatisticPanel ( ) { } public void initActions ( ) { } public void addWeekButtonListener ( ActionListener al ) { } public void addMonthButtonListener ( ActionListener al ) { } public void addYearButtonListener ( ActionListener al ) { } public void initStatistic ( ) { setBorder ( new EmptyBorder ( 50 , 30 , 50 , 50 ) ) ; setLayout ( new BorderLayout ( 50 , 50 ) ) ; upperPanel = new JPanel ( new GridLayout ( 1 , 3 , 40 , 40 ) ) ; <START_BUG> lowerPanel = new JPanel ( new GridLayout ( 1 , 3 ) ) ; <END_BUG> weekButton = new JButton ( "Vecka" ) ; upperPanel . add ( weekButton ) ; monthButton = new JButton ( "Månad" ) ; upperPanel . add ( monthButton ) ; yearButton = new JButton ( "År" ) ; upperPanel . add ( yearButton ) ; String [ ] [ ] title = new String [ ] [ ] { new String [ ] { "Exempel" } } ; String [ ] titleColumns = new String [ ] { "Titel" } ; DefaultTableModel titleModel = new DefaultTableModel ( title , titleColumns ) ; titleTable = new JTable ( titleModel ) ; String [ ] [ ] amount = new String [ ] [ ] { new String [ ] { "Exempel" } } ; String [ ] amountColumns = new String [ ] { "Antal" } ; DefaultTableModel columnsModel = new DefaultTableModel ( amount , amountColumns ) ; amountTable = new JTable ( columnsModel ) ; String [ ] [ ] cashIn = new String [ ] [ ] { new String [ ] { "Exempel" } } ; String [ ] cashInColumns = new String [ ] { "Intäkter" } ; DefaultTableModel cashInModel = new DefaultTableModel ( cashIn , cashInColumns ) ; cashInTable = new JTable ( cashInModel ) ; firstPane = new JScrollPane ( titleTable ) ; firstPane . setHorizontalScrollBarPolicy ( JScrollPane . HORIZONTAL_SCROLLBAR_ALWAYS ) ; firstPane . setVerticalScrollBarPolicy ( JScrollPane . VERTICAL_SCROLLBAR_ALWAYS ) ; firstPane . setViewportBorder ( new LineBorder ( Color . BLUE ) ) ; secondPane = new JScrollPane ( amountTable ) ; secondPane . setHorizontalScrollBarPolicy ( JScrollPane . HORIZONTAL_SCROLLBAR_ALWAYS ) ; secondPane . setVerticalScrollBarPolicy ( JScrollPane . VERTICAL_SCROLLBAR_ALWAYS ) ; secondPane . setViewportBorder ( new LineBorder ( Color . BLUE ) ) ; thirdPane = new JScrollPane ( cashInTable ) ; thirdPane . setHorizontalScrollBarPolicy ( JScrollPane . HORIZONTAL_SCROLLBAR_ALWAYS ) ; thirdPane . setVerticalScrollBarPolicy ( JScrollPane . VERTICAL_SCROLLBAR_ALWAYS ) ; thirdPane . setViewportBorder ( new LineBorder ( Color . BLUE ) ) ; rubrik = new JLabel ( "Bästsäljande<seq2seq4repair_space>böcker" , JLabel . CENTER ) ; lowerPanel . add ( firstPane ) ; lowerPanel . add ( secondPane ) ; lowerPanel . add ( thirdPane ) ; this . add ( rubrik , BorderLayout . SOUTH ) ; this . add ( upperPanel , BorderLayout . NORTH ) ; this . add ( lowerPanel , BorderLayout . CENTER ) ; } }

Fix:
lowerPanel = new JPanel ( new GridLayout ( 1 , 3 , 20 , 20 ) ) ;